Functional neurological disorder is a common and phenomenologically diverse condition. Resultant disability is caused by both the dominant clinical presentation, e.g. paralysis or tremor and additional symptomatology such as cognitive symptoms. Recently the similarity of neuropsychiatric profiles across a range of functional syndromes has been highlighted. This is suggestive of a common underlying mechanism with a theoretical deficit of information processing proposed. Identification of an experimental biomarker for such deficits could offer novel assessment and therapeutic strategies. In this study, we took the temporal discrimination threshold as a paradigm that can be used to model sensory processing in functional movement disorders. Our hypothesis was that we would be able to delineate markers of slowed information processing in this paradigm removed from the phenomenological presentation with a movement disorder. We recorded both response accuracy and reaction time in a two-choice temporal resolution/discrimination task in 36 patients with functional movement disorders and 36 control subjects. A psychometric function was fitted to accuracy data for each individual revealing both abnormally high threshold values (P = 0.0053) and shallow psychometric slopes in patients (P = 0.0015). Patients with functional movement disorders also had significantly slower response times (P = 0.0065). We then used a well-established model for decision-making (the drift diffusion model) that uses both response accuracy and reaction time data to estimate mechanistic physiological dimensions of decision-making and sensory processing. This revealed pathologically reduced drift rate in the patient group, a parameter that quantifies the quality and rate of information accumulation within this sensory task (P = 0.002). We discuss how the deficits we observed in patients with functional movement disorders are likely to stem from abnormal allocation of attention that impairs the quality of sensory information available. Within a predictive coding framework sensory information could be down-weighted in favour of predictions encoded by the prior. Our results therefore offer a parsimonious account for a range of experimental and clinical findings. Reduced drift rate is a potential experimental marker for a generalized deficit in information processing across functional disorders that allows diverse symptomatology to be quantified under a common disease framework.

中文翻译：

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漂移率降低：功能性运动障碍中信息处理受损的生物标志。

功能性神经障碍是一种常见的现象学上多样的疾病。结果性残疾是由主要的临床表现（例如麻痹或震颤）和其他症状（例如认知症状）引起的。最近，人们已经强调了跨一系列功能综合征的神经精神病学特征的相似性。这暗示了一种常见的潜在机制，并提出了理论上的信息处理缺陷。针对此类缺陷的实验性生物标志物的鉴定可以提供新颖的评估和治疗策略。在这项研究中，我们将时间歧视阈值作为可用于对功能性运动障碍的感觉处理进行建模的范例。我们的假设是，我们将能够描述从运动障碍的现象学表现形式中删除的这种范例中信息处理速度减慢的标记。我们在两项选择的时间分辨/区分任务中记录了36位功能性运动障碍患者和36位对照对象的反应准确性和反应时间。将心理测验函数拟合到每个人的准确性数据，以揭示患者异常高的阈值（P = 0.0053）和患者的心理测验斜率较浅（P = 0.0015）。功能性运动障碍患者的反应时间也明显减慢（P = 0.0065）。然后，我们使用完善的决策模型（漂移扩散模型），该模型使用响应准确度和反应时间数据来估计决策和感觉处理的机械生理尺度。这揭示了患者组在病理上降低的漂移率，该参数量化了该感官任务内信息积累的质量和速率（P = 0.002）。我们讨论了我们在功能性运动障碍患者中观察到的缺陷如何可能源自注意力的异常分配，从而损害了可用的感官信息的质量。在预测编码框架内，可以减少感官信息的权重，以有利于由先验编码的预测。因此，我们的结果提供了对一系列实验和临床发现的简化解释。